Scanning device for magnetic tape with special disposition of rotary transformers for recording and playback magnetic heads

Abstract

For oblique track scanning of magnetic tape which is looped around a two-part drum (1, 2) separated by a gap (5) in which magnetic heads (11) affixed to a headwheel revolve, the rotary transformers connecting the magnetic heads on the headwheel to fixed parts of the scanning device are provided by inner and outer magnetic core rings in which windings are embedded for a number of transformers. One group of these rotary transformers (18, 19) is located above the headwheel disk structure (10, 25) in such a way that outer magnetic core rings are fixed in a bore of the fixed upper drum (1) and inner magnetic core rings (19) are affixed to a seating shell (25) that connects the headwheel disk (10) to its driving shaft. Another group of rotary transformers (10, 21) is located beneath the rotary headwheel disk structure (10, 25) and in this case the outer magnetic core rings (20) are affixed to the inner wall of the rotary headwheel disk structure (10, 25) and the inner magnetic core rings are affixed to the outer wall of the bearing (15) of the shaft (14) that drives the rotary headwheel disk.

We claim: 
     
       1. A scanning device for a magnetic tape recording and playback apparatus having a composite tape guiding drum consisting of fixed upper and lower drums, having a rotary headwheel disk structure mounted on a shaft and having at least two magnetic heads affixed to the periphery of said headwheel disk structure, at least two rotary transformers being provided for transmission of signals from and to the magnetic heads, including, above the headwheel disk structure, at least one of said rotary transformers and, below the headwheel disk structure, at least one of said rotary transformers, characterized in that said headwheel disk structure (10, 25) includes a disk-seating shell (25), and in that   each said rotary transformer consists of an outer magnetic core ring with an embedded winding and an inner magnetic core ring with an embedded winding, said outer magnetic core rings include at least two core rings respectively on opposite sides of said headwheel disk structure (10, 25) and disposed one above the other and said inner magnetic core rings include at least two core rings respectively on opposite sides of said headwheel disk structure (10, 25) and disposed one above the other, said windings of said rotary transformers embedded in said core rings above and below said headwheel disk structure being so connected that said at least one rotary transformer which is above said headwheel disk structure (10, 25) has its said outer magnetic core ring fixed in a bore of said fixed upper drum (1) and has its said inner magnetic core ring fixed on said disk-seating shell (25) of said rotary headwheel disk structure (10, 25), and said at least one rotary transformer which is below said headwheel disk structure (10, 25) has its said outer magnetic core ring affixed to the inner wall of the rotary headwheel disk structure (10, 25) and has its said inner magnetic core ring affixed to an outer wall (16a) of a bearing for the shaft (14) of said rotary headwheel disk structure (10, 25), each said outer magnetic core ring and its embedded winding being uniformly radially adjacent to and concentric with each respective said inner magnetic core ring and its said embedded winding of the same rotary transformer.   
     
     
       2. The scanning device of claim 1, wherein said at least one rotary transformer located on a first side of the rotary headwheel disk structure (10, 25) is connected for transmission of playback signals from at least one playback head which is included in said at least two magnetic heads, while said at least one rotary transformer located on a second side, opposite to said first side, of said rotary headwheel disk structure (10, 25) is connected for transmission of signals other than playback signals from at least one non-playback magnetic head which is included in said at least two magnetic heads. 
     
     
       3. The scanning device of claim 1, wherein respective tips (11) of said at least two magnetic heads (12) affixed to the periphery of said rotary headwheel disk structure define an orbit plane of said magnetic heads and wherein means are provided for coaxially aligning and affixing said upper and lower drums (1, 2) of said composite tape guiding drum (3) which comprise a drum bracket (4', 4") composed of two parts fitting together at the height of the orbit plane of said magnetic heads (12,), said drum bracket having a prismatic surface which fits a prismatic portion of the periphery of said drums, each separate part (4', 4") of said drum bracket being firmly connected respectively to said upper and lower drums in each case by at least one screw connection directed perpendicularly to the direction of the axis of said shaft (14). 
     
     
       4. A scanning device for a magnetic tape recording and playback apparatus having a composite tape guiding drum consisting of fixed upper and lower drums, having a rotary headwheel disk structure mounted on a shaft and having at least four magnetic heads affixed to the periphery of said headwheel disk structure, at least two rotary transformers being provided for transmission of signals from and to the magnetic heads, including at least one of the rotary transformers located above the headwheel disk structure and at least one of said rotary transformers located below the headwheel disk structure, characterized in that said apparatus has at least four said rotary transformers for transmission of signals from and to said magnetic heads, including at least two located below and at least two located above said headwheel disk structure, in that   said headwheel disk structure (10, 25) includes a disk-seating shell (25) and in that   each said rotary transformer consists of an outer magnetic core ring with an embedded winding and a concentric inner magnetic core ring with an embedded winding, said outer magnetic core rings being provided in respective coaxial groups stacked one above the other on opposite sides of said headwheel disk structure (10, 25) and said inner magnetic core rings being provided in respective coaxial groups stacked one above the other on opposite sides of said headwheel disk structure (10, 25), all said magnetic core rings being disposed and their embedded windings being connected in such a way that said at least two rotary transformers which are located above said headwheel disk structure (10, 25) have their said outer magnetic core rings fixed in a bore of said fixed upper drum (1) and have their said inner magnetic core rings fixed on said disk-seating shell (25) of said rotary headwheel disk structure (10, 25), and said at least two rotary transformers which are located below said headwheel disk structure (10, 25) have their said outer magnetic core rings affixed to an inner wall of the rotary headwheel disk structure (10, 25) and have their said inner magnetic core rings affixed to an outer wall (16') of a bearing for the shaft (14) of said rotary headwheel disk structure (10, 25), each said outer magnetic core ring and its embedded winding being uniformly radially adjacent to and concentric with each respective said inner magnetic core ring and its said embedded winding of the same rotary transformer.   
     
     
       5. The scanning device of claim 4, wherein said at least two rotary transformers located on a first side of the rotary headwheel disk structure (10, 25) are connected for transmission of playback signals from at least two playback head which are included in said at least four magnetic heads, while said at least two rotary transformer located on a second side opposite to said first side, of said rotary headwheel disk structure (10, 25) are connected for transmission of signals other than playback signals from at least two non-playback magnetic heads which are included in said at least four magnetic heads. 
     
     
       6. The scanning device of claim 4, wherein respective tips (11) of said at least four magnetic heads (12) affixed to the periphery of said rotary headwheel disk structure define an orbit plane of said magnetic heads and wherein means are provided for coaxially aligning and affixing said upper and lower drums (1, 2) of said composite tape guiding drum (3) which comprise a drum bracket (4', 4") composed of two parts fitting together at the height of the orbit plane of said magnetic heads (12,), said drum bracket having a prismatic surface which fits a prismatic portion of the periphery of said drums, each separate part (4', 4") of said drum bracket being firmly connected respectively to said upper and lower drums in each case by at least one screw connection directed perpendicularly to the direction of the axis of said shaft (14). 
     
     
       7. The scanning device of claim 4 wherein said rotary transformers are of identical construction and dimensions at least in their magnetic core rings, the windings embedded in said magnetic core rings and the spacing between windings embedded in adjacent outer and inner core rings and between adjacent outer and inner core rings.